LAUSR

Abstract Nickel-doped copper selenide—Cu2-xNixSe (x = 0; 0.01; 0.02; 0.03)—materials with high thermoelectric properties were synthesised through reduction of reagents in hydrogen. The impact of the nickel content on both the microstructure and thermoelectric properties was examined. The nickel-doped samples’ microstructure differed significantly from pristine copper selenide. Besides Cu2Se, copper precipitations were present in the materials. The presence of the metallic nanoparticles in the nickel-doped materials enhanced the electrical conductivity without significantly changing the Seebeck coefficient. Above 500 K, the structure of the doped samples also resulted in decreased thermal conductivity. Also, the impact of the Cu2Se phase transition on thermoelectric properties is visible. The highest ZT value, equal to 0.8 at 650 K, was reached for the Cu1.98Ni0.02Se sample.